bootstrap 4 sticky header on scroll code example
Example 1: bootstrap sticky top
<div class="sticky-top">...</div>
Example 2: bootstrap responsive sticky top
<div class="sticky-sm-top">Stick to the top on viewports sized SM (small) or wider</div>
<div class="sticky-md-top">Stick to the top on viewports sized MD (medium) or wider</div>
<div class="sticky-lg-top">Stick to the top on viewports sized LG (large) or wider</div>
<div class="sticky-xl-top">Stick to the top on viewports sized XL (extra-large) or wider</div>